Synthesis of Nitroalkanes from Alkylhalides under Mild and Nonaqueous Conditions by Using Polymer Supported Nitrites

Alkyl halides are efficiently converted to their corresponding nitroalkanes under mild and nonaqueous conditions by using polymer supported nitrites. The polymeric reagent is regenerable.     

Mononitration of phenol derivatives by guanidinium nitrate and silica sulfuric acid under mild conditions

A mixture of guanidinium nitrate and silica sulfuric acid acts as mild and heterogeneous media for the efficient mono nitration of phenolic compounds in dichloromethane at room temperature.     

Melamine-(H_2SO_4)_3 and PVP-(H_2SO_4)_n as solid acids:Synthesis and application in the first mono-and di-nitration of bisphenol A and other phenols

Melamine and poly vinylpyrrolidone（PVP） reacted with neat sulfuric acid readily to form two new organic solid acids namely melamine-（H₂SO₄）₃ and PVP-（H₂SO₄）_n.These solid acids were used for the first nitration of bisphenol A as well as other phenols in the presence of NH₄NO₃.Mono- and di-nitro bisphenol A have been characterized with IR and ¹H NMR techniques.     

Reaction of some 4,6-dimethoxyindoles with nitric acid: nitration and oxidative dimerisation

A range of 3-substituted-4,6-dimethoxyindoles bearing electron-withdrawing groups in either the 2- or 7-position, can be nitrated using nitric acid in acetonitrile, to give 7-nitro and 2-nitro-indoles, respectively. Those without electron-withdrawing groups undergo oxidative dimerisation at C7, if 2,3-disubstituted, and at C2, if N-methylated and unsubstituted at C2.     

CH3COOH.TiO2: An excellent catalyst for the green nitration of toluene by N2O4

The solvent-free nitration of toluene with N₂O₄ gas over solid acid catalysts is a green reaction for preparing the mono-nitrotoluene (NT) isomers. The acid-modified catalysts are more efficient than common catalysts for this type of reaction. For this purpose, a titanium dioxide (TiO₂) catalyst is synthesized with a sol-gel method and modified by acetic acid to increase catalytic properties. The acid-modified TiO₂ (CH₃COOH·TiO₂) is characterized by different analyses. To optimization of toluene nitration conditions, reaction temperature (X₁) (30 < X₁ < 60 °C), N₂O₄/toluene molar ratio (X₂) (0.5 < X₂ < 2), and the amount of catalyst (X₃) (0.05 < X₃ < 0.3 g) factors were investigated by Minitab software with the CCD-RSM. Three responses including the selectivity of meta-NT isomer (S_m), the ratio of para-NT to ortho-NT selectivity (S_p/o), and the selectivity of by-products (S_bp) were considered for the optimization. Statistical parameters were applied to evaluate the goodness of fitting for the models. Optimum values for X₁, X₂, and X₃ parameters are 57.9 °C, 1.91, and 0.25 g, respectively. The conversion of toluene under these conditions is 93.2%. The comparison of S_m, S_p/o, and S_bp in CH₃COOH.TiO₂ (1.51%, 0.8, and 5.48%, respectively) with Fe₂O₃ (8.5%, 0.43, and 20.57%, respectively), SiO₂ (8.43%, 0.48, and 16.24%, respectively), TiO₂ (5.9%, 0.57, and 13.87%, respectively), TiO₂–Fe₂O₃ (4.72%, 0.64, and 9.18%, respectively), and TiO₂–SiO₂ (4.42%, 0.67, and 5.73%, respectively) catalysts show that this catalyst has a low S_m and S_bp as well as a higher S_p/o than other mentioned catalysts. The mechanism of the mentioned reaction is reviewed in the presence of CH₃COOH·TiO₂ catalyst. The high stability of the CH₃COOH·TiO₂ is proved by the reusability test, and it is found that its stability against inactivation is more than the TiO₂ catalyst.     

Synthesis of calix[4]arene(amido)monocrowns and their photoresponsive derivatives

A series of new calix[4]arene(amido)mono-crown compounds have been synthesized through aminolysis of calix[4]arene esters and intramolecular cyclization of the intermediates. The title compounds were converted into their nitro and azo substituted derivatives to provide novel photoresponsive molecular receptors for transition metal ions. Single crystal X-ray analysis of calix[4]arene(ethyleneamido)mono-crown (2a) revealed that the compound is present in a cone conformation with an amido loop that caps the lower rim of calix[4]arene cavity to result in stacking along axis a and axis c to provide supramolecular aggregates in the solid state. Evaluation of synthesized macrocycles in the solution phase for recognition of transition metal cations (Cr³⁺, Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺, Ag⁺, Cd²⁺, Pb²⁺, Hg⁺, Hg²⁺, Pd²⁺, and Pt²⁺) by UV-visible spectroscopy revealed that p-tert-butyl-calix[4]arene mono-(amidocrown) 1c selectively shows a blue shift at 38 nm on interaction with Hg⁺ ions.     

A new method for the mononitration of phenol derivatives by poly(4-vinylpyridinium nitrate) and silica sulfuric acid under mild conditions

This procedure works efficiently for high selective mono nitration of phenol and substituted phenol to corresponding nitro compounds in moderate to high yield using poly(4-vinylpyridinium nitrate) and silica sulfuric acid in dichloromethane at room temperature.     

6，6‘—二甲氧基—4，5，4’,5‘—二亚甲基二氧基—2，2’—联苯二甲酸二甲酯及其衍生物的合成研究

以没食子酸为原料经酯化、醚化、区域选择性硝化、还原、Sanmeyer及分子间Ulmann耦合等反应以较高产率合成6,6‘-二甲氧基-4,5,4‘,5‘-二亚甲基二氧基-2,2‘-联苯二甲酸二甲酯（β-联苯双酸,β-DDB）,并对其进行衍生化,得到5个β-DDB的衍生物,用IR,^1H NMR和MS等鉴定了其结构,使用手性柱对β-DDB进行拆分得到了两个对映异体,利用圆二色谱确定了它们的立体构型。     

Nitric acid in the presence of P2O5 supported on silica gel—a useful reagent for nitration of aromatic compounds under solvent-free conditions

A variety of aromatic compounds are nitrated to parent nitro aromatic compounds under solvent-free conditions using 65% nitric acid in the presence of P₂O₅ supported on silica gel is described. This methodology is useful for nitration of activated and deactivated aromatic rings.     

Ultrasonic-assisted environmentally-friendly synergetic synthesis of nitroaromatic compounds in core/shell nanoreactor: A green protocol

An efficient sonochemical protocol for the nitration of aromatic compounds was described in the presence of a catalytic amount of sulfuric acid-functionalized silica-based core/shell magnetic nanocomposite at room temperature in an eco-friendly and recyclable media, deep eutectic solvent (DES), based on choline chloride and urea. The particle size, morphology and elemental analysis of the core/shell nanocatalyst were carried out by TEM, SEM, EDX and XRD analyses. The nanocatalyst and DES were easily recovered from the reaction mixture quantitatively and reused several times.